Binary Light Beam Deflection in Single Crystal Barium Titanate.
Final technical rept. Jan 66-Jun 70,
JOHNS HOPKINS UNIV BALTIMORE MD CARLYLE BARTON LAB
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The paper describes a new type of binary electro-optic light beam deflector capable of wide angle deflection. A linearly polarized light beam is deflected to total internal reflection at the boundary of a 90 degree domain wall wedge in single crystal barium titanate. The wedge is moved through the crystal by an applied electric field. The crystal is held at a temperature where it is ferroelectric, birefringent, and has tetragonal 4mm symmetry. The angle of deflection can be set at any angle from 0 degrees to 45 degrees, limited only by the exit aperture of the temperature bath. The electric field required to operate the deflector varies from approximately 200Vmm at 80C to less than 50Vmm at 130C. It is shown theoretically and experimentally that a threshold field exists for the operation of the beam deflector, and that this threshold field is a function of temperature. The operating frequency of the deflector is limited by heating effects, and the switching risetime is limited by the presence of 180 degree domain walls. Two possible modes of operation are suggested 1 continuously operating binary switch, and 2 gated switch. Author